Which poetic technique is illustrated throughout the entire poem Happiness Epidemic?

Allusion, which is a figure of speech in which you covertly or indirectly refer to an object or circumstance, like the analogy between a disease and the spread of happiness.

Explanation:

Allusion could be a figure of speech, during which one refers covertly or indirectly to AN object or circumstance from an external context. It is left to the audience to form the connection; where the affiliation is directly and expressly expressed (as hostile indirectly implied) by the author, it's instead sometimes termed a reference. In the arts, a literary reference puts the alluded text during a new context beneath that it assumes new meanings and denotations.

Allusion, which is a figure of speech in which you covertly or indirectly refer to an object or circumstance, like the analogy between a disease and the spread of happiness.